The present invention generally relates to disposable underpants and, more particularly, to a method for manufacturing such diapers in the form of underpants and infant training shorts.
Various approaches to such underpants or shorts have already been well known from, for example, Japanese Patent Application Disclosure Gazettes Nos. 1982-77304 and 1982-117602. These Gazettes disclose the methods for attachment of the elastic members to the waist-hole and the leg-holes of the underpants, particularly along the curves of the respective leg-holes so as to improve a fitness around the wearer's legs.
In order to ensure that a continuous elastic member can be continuously attached to web at locations to be formed into the waist-hole and the leg-holes, respectively, during continuous manufacturing basic bodies of underpants from said web, it is generally required that such continuous elastic member must be kept stretched at a predetermined ratio when it is attached to said web at said locations with use of suitable adhesive. Turning to the above-referred prior art, they disclose the procedure in which the continuous elastic member carrying said adhesive previously applied thereon is attached to the continous web.
Generally, when the elastic member is attached to the web while the elastic member is curved according to the curve, for example, of the leg-hole, the elastic member tends to restore its initial rectilinearity, due to its contractility, and sometimes to be attached to the web at a location deviating from the proper location at which the elastic member should be attached to the web.
Such undesirable deviation or shift of the elastic member may occur also in the above-referred prior art because, according to such prior art, the elastic member carrying adhesive previously applied thereon must be attached to fibrous nonwoven fabric having its surface usually less smooth than that of plastic film and an adhesive effect is correspondingly low. This necessarily makes any high speed handling difficult. When the elastic member is continuously attached to the web while the elastic member is curved so as to follow the curve of the leg-hole under control of traverse means, a certain quantity of adhesive is inevitably transferred onto the traverse means as the elastic member carrying adhesive previously applied thereon passes by the traverse means. Thus, the elastic member is peeled off or displaced to deteriorate the adhesive effect and inconveniently requires frequent cleaning of the traverse means particularly at the portion thereof where the elastic member passes by.
Accordingly, it is a primary object of the invention to provide a method for manufacturing disposable diapers allowing the above-mentioned problem conventionally encountered by the prior art to be solved by attaching the elastic member to the web along an annular adhesive zone in each location to be formed into a leg-hole wherein said annular adhesive zone is defined by a strip of adhesive having a width larger than that of the elastic member.